Port monitors can send two types of messages to the SAC. The type of
message is indicated by setting the pm_type field
of the pmmsg structure to one of the following values:

PM_STATUS state information

PM_UNKNOWN negative acknowledgement

For both types of messages, set the pm_tag
field to the port monitor's tag and the pm_state
field to the port monitor's current state. Valid states are:

PM_STARTING starting

PM_ENABLED enabled

PM_DISABLED disabled

PM_STOPPING stopping

The current state reflects any changes caused by the last message from
the SAC.

The status message is the normal return message. The negative acknowledgement
should be sent only when the message received is not understood.

pm_size indicates the size of the optional-data
part of the message. pm_maxclass is used to specify
a message class. Both fields are discussed in Message Classes. In the Solaris environment, always set pm_maxclass to 1 and sc_size
to 0.

Port monitors can never initiate messages; they can only respond to
messages that they receive.